Steam cylinder oil and process of preparing the same



Patented Feb. 11, 1941 STEAM CYLINDER OIL AND PROCESS OF PREPARING THESAME Arthur Lazar, Berkeley, and Joseph V. Crenna,

Concord, Calif., assignors to Tide Water Associated Oil Company, SanFrancisco, Calif., a corporation of Delaware No Drawing. Originalapplication June 11, 1937,

Serial No. 147,784. Divided and this application February 2,1939, SerialNo. 254,310

3 Claims.

This invention relates to the treatment of lubricating oil to insurestability under conditions of high temperatures and pressures in thepresence of steam and has for a particular ob ject the preparation of alubricating oil especially adapted to function in the cylinders of steamengines.

In the manufacture of steam cylinder oils certain specifications must bestrictly adhered to because of operating conditions peculiar to the useof such oils.

Steam cylinderoils may not be supplied to the walls of the pistons andcylinders of the engine in many of the well-known forms of lubrication,but are introduced to the cylinder with the steam in such fashion thatthey are finely divided by atomization, whereby they are spread evenlyover the moving parts.

In the modern steam engine practice the temperature of the steam in thecylinder of the en gine when closed by the piston goes as high as 500F., under its corresponding pressure, and under such conditions it ishighly important not only that a proper distribution of the oil isassured,-but also that the stability of the oil is such as to resistdecomposition, whereby undesirable deposits, such as coke, and the like,are eliminated. v

Oils which have a tendency to emulsify with steam are best suited forsteam cylinder oils and heretofore it has been common practice tocompound with a mineral oil a certain percentage of a fatty oil, such astallow, which causes emulsification. Such fatty oil, or oils, usuallyrepresent up to 8% to 10% of the mineral oil, but in addition to beingcostly, are decomposed at high temperatures which do not affect themineral oil hydrocarbons, thus forming free fatty acids which attackmetals under such temperature conditions.

Although high viscosity oils are generally applicable to steamcylinder'lubrication, this factor is not necessarily limiting as theinvention involves the preparation of an oil which will provide adequatelubrication while possessing an inherent quality of stability undersevere conditions of high temperature and in the presence of steam.

This invention provides a way of insuring the stability of steamcylinder oils while emulsifying the same under operating conditions,which is preferably accomplished in the following manher.

As a base stock for steam cylinder oils it is preferred to select alubricating oil which is composed mainly of saturated hydrocarbons, suchoil, for example, being an asphaltic base, or mixed base, oil, which ishighly refined by treatment with liquid sulphur dioxide, as in theWelllmown Edeleanu process, to remove unsaturated hydrocarbons,aromatics, etc. Such lubricating oil, thus treated, shows the greateststability under high heat conditions, but, of course, a body ofsaturated hydrocarbons may also be prepared by extensive sulphuric acidtreatment, or even distilled from certain stocks, such as Pennsylvaniacrudes.

It has been found, however, that certain oils of less saturatedcharacter can be stabilized by the processing method herein described.Such oils may include distillates from asphaltic or mixed base crudes,as well as lubricating oils obtained from such distillates bycomparatively mild refining operations, such as the conventional acidtreatment.

To the base lubricating oil is added a polyvalent metal soap, as lime ormagnesium soap, of an organic acid, such for example as oleic acid,stearic acid, palmitic acid, naphthenic acids, or sulphonic acid, theproportion of such added soap ranging from very small percentages of theoil, e. g., .01% to .1% up to the limit of solubility of said soap insaid oil.

The alkaline earth metals, calcium, strontium, barium, and magnesium,yield soaps with organic acids which exhibit suitable stabilizingqualifications. When such soaps of a stable nature are added to oils,the resistance of the lubricant to decomposition, particularly under thehigh temperatures encountered in steam cylinder lubrication and otherservices, is greatly improved, and as a feature necessary for steamcylinder lubrication we again emphasize the necessity of a stablecompounded lubricant as heretofore outlined.

We have found that the alkaline earth metal soaps do not formincrustations in service and of these calcium and magnesium soaps arepreferred for economical reasons. However, the soaps of cadmium,aluminum, zinc, lead, copper, chromium, manganese, iron, cobalt, nickel,tin and mercury, may also be used.

Any organic acid which will yield a polyvalent metal soap with suitablestabilizing properties, is applicable to the process; Fatty acids, forexample, oleic, stearic, palmitic, and derivatives of the same, havebeen successfully employed.- 0f the fatty acids we prefer to use thoseof fourteen or more carbon atoms. Normally the more saturated acids, asstearic and palmitic, yield soaps which are less soluble in oil than theunsaturated acids, e. g., oleic, but a saturated acid of excellentsolubility may be obtained through the hydrogenation of unsaturatedacids of certain types.

To illustrate; unsaturated acids from. flsh oil when hydrogenated, yieldacids which can be made into polyvalent metal soaps having superior oilsolubility properties. The acids from fish oils may be obtained in largequantities by splitting the esters normally present therein.

Polyvalent metal soaps of the hydrogenated acids derived as abovedescribed are soluble in 011 up to 5 per cent by weight, and are veryefllcient stabilizing agents.

Sulphonic acid soaps are yery soluble in oil.

Acids of this type which have been found particularly suitable, may bederived from the sulphonation of 80 to 200 seconds, Saybolt Universal100 oils of asphaltic origin, or raflinates derived therefrom by thewell known Edeleanu treatment with liquid sulphur dioxide. Also from theextracted portion of the Edeleanu treatment aromatic type 'sulphonicacids may be prepared, from which suitable polyvalent alkaline earth orother metal aromatic sulphonic acid soaps can be made for the describedpurpose.

Polyvalent metal soaps of the naphthenic acids are normally more oilsoluble than those of the fatty acids, and are excellent stabilizing andemulsifying agents. of the naphthenates those of calcium, magnesium,tin, and aluminum are preferred.

Depending largely on the dgeree of emulsiilcation and the stabilizinginfluence desired, the content of soaps dissolved in the oil may varyfrom a minute amount up to the limit of oil solubility. The followingtable is illustrative of the solubilities of the calcium soaps in theoil.

Turn I Solubility in Solubility in oils of aspbaltic paraiilne oilsorigin Calcium sulphonate, 50% or more 50% or more. Calcium naphthenatcCalcium oleatc Calcium stearate.. Calcium palmitatm"; 0.1 0 max"... 0.3%max The above soaps are listed in the order of: Decreasing solubility inoil, Increasing qualifications as lubricant stabilizers, Decreasingemulsifying properties.

A table similar to the above can be prepared quite as stable.

Aluminum soaps of organic acids show excellent solubility in mineraloils of all types. However, when added in percentages in excess of about2%, the compounded oils possess a stringy structure, which for ourpurposes is undesirable. The preferred range for aluminum soaps isbetween 0.01% up to 1.0% by weightof the oil.

In the preparation of lubricants we have also found that the solubilityof the less soluble polyvalent metal soaps can be increased by themixing therewith of a more soluble soap of polyvalent metals. Forexample, the solubility of calcium oleate can be tremendously increasedby the simultaneous incorporation in the lubricant of a comparativelysmall percentage of a more soluble calcium or other polyvalent metalsoap, such as calcium naphthenate or calcium sulphonate.

This is a particularly important feature when it is desired topermanently incorporate in the oil soaps of relatively low solubility.The following table ,clearly illustrates this feature, and it should benoted that the solubility of calcium oleate in the same oil.v and imderthe same conditions has been increased 'manyfold by the addition of asmall percentage of a more soluble soap.

TABLIII Solubility of calcium oleate in California lubricatina oil Percent Calcium olea 1.0 .Calcium oleate+10% calcium naphthenate 2.5Calcium oleate+20% calcium naphthenate..- 4.0 Calcium oleate+30% calciumnaphthenate 7.0 Although in the above example calcium naphthenate hasbeen shown because of its well known oil solubility feature, this in noway should be indicated. as a limitation on this feature, and a similarresult is obtained by the use of other more soluble soaps, such as thepolyvalent metal soap of sulphonic acid. I

In describing this invenion which is particlarly directed towards themanufacture of a steam cylinder oil of stable oil and soapcharacteristics,

-. advantageous to utilize stable soaps made from a mixture of acids. I

In order to provide the maximum stability to resist the high temperatureconditions encountered, and still provide enough soap for properlubrication in conjunction with steam or otherwise, such emulsiflableoil should contain a maximum quantity of the preferred soaps describedherein.

The novel feature of mixing two or more soaps is utilized when it isdesired toincrease the solubility of the more insoluble polyvalent metalsoaps in oil over the maximum noted in Table I.

The following table is illustrative of the quantitles of polyvalentmetal soaps normally added to the oil and the preferred range of soapcontent for the steam cylinder oils.

Tun: III

a Preferred Range mas Percent Percent Sulphonates Up to 5 0.01 to 2 NUpto5 0.01 to 1.0 UptolO, 0.0lto0.l Steal-ates Up to 0 8 0.01 to 0.1Palmitates Up to 0 3-- 0.01 to 0.1

It is important in the application of the above ranges of soap contentto lubricants to add just suilicient soap to give the desiredstabilization properties. such as to give the desired emulsifyingproperties and prevent the formation of incrustations or deposits on thecylinder walls of the lubricated mechanism. In general the addition isso small that the amount of ash arising from its use as an emulsifier istoo small to be determined analyti cally.

The use of soap results in a steam cylinder oil of unimpaired stabilitywhich emulsitles sumciently to get the desired distribution, the soapsbeing easily combined with the saturated hydrocarbons, due to their oilsolubility.

Likewise, a steam cylinder oil having the required emulsifyingproperties may be prepared from oils which result from the distillationof a suitable crude stock and which may be naturally composed mainly ofsaturated hydrocarbons. For instance, residual oils of Pennsylvaniaorigin when traces of oxides, or hydroxides, are added to the oil whenheated, such oil develops the desired pronounced emulsifying properties.To such oils, an organic acid or acids not normally present in petroleummay be added, and the requisite amount of polyvalent metal oxide orhydroxide, to accomplish substantial neutralization of the oils,applied.

A preferred amount of polyvalent metal oxide or hydroxide, for example,magnesium oxide, or lime, or other alkaline earth oxide, or hydroxide,which may be added to such residual oil varies from 0.01% to 0.1%, andsuch is incorporated in the oil by intimate mixing at elevatedtemperatures, preferably about 300' E, and generally in excess ofatmospheric temperatures. This oil may then be used as straight steamcylinder oil, or may be blended in amounts of from 10% to 20% with abody of a highly refined oil of high stability, such as the SO; treatedoil previously described.

The soaps may be added directly to the oil, during agitation eithermechanically or with air, and the oil heated to 200-300" F. Thepreferred method however, is to first dissolve the desired quantity oforganic acid in the oil and slowly add a metallic oxide or hydroxide, ofthe polyvalent metals previously cited, heating preferably to about 300F., and generally in excess of atmos- In steam cylinder oils theaddition is pheric temperature, and agitating the mixture untilneutralization of the free acid is substantially complete. In suchmanner the soap is more readily incorporated in the oil and excellentdistribution and dispersion of the soap in the oil is accomplished. Whenprepared in this manner with excess quantities of acid and oxide thequantity of the soap which is retained in the oil represents the maximumof solubility. This oil may be used as is, or blended in amounts from10% to 50% with additional quantities of suitable base oils.

vWhile it is unnecessary, the use of small amounts of an acidless fattyoil with the steam cylinder oils prepared as above described, hassometimes a beneficial eflect in lowering the surface tension, but thequantity used, from 0% to 3% is kept as low as possible and in any eventis far less than the amount normally used in compounding steam cylinderoils.

This application is a division of our copendlng application SerialNumber 147,784 flied June 11, 1937 which is a continuation in part ofour copending applications, now Patents Nos.

2,084,531-2, dated June 22, 1937.

We claim:

1. A steam cylinder oil consisting mainly of saturated hydrocarbonssubstantially devoid of free organic acids, and containing a smallpercentage of a polyvalent metal soap of comparatively low solubilitywith a still smaller percentage of a more soluble polyvalent metal soap,the total percentage of the soaps being insuflicient to leave anappreciable deposit of ashwhen the mixture is injected into the cylinderof a steam engine.

2. The method of increasing the solubility of a relatively low solublealkaline earth metal soap such as calcium oleate. in a steam cylinderlubricating oil, which consists in incorporating with the oil and soap amore soluble alkaline earth metal soap, such as calcium naphthenate, inamount less than the less soluble soap, the total amount of the twosoaps together being between and 1% of the weight of the oil.

3. A lubricating oil containing up to one percent of a soap mixtureconsisting of calcium oleate and calcium naphthenate, the naphthenatebeing less than 40% of the weight of the oleate.

ARTHUR LAZ'AR. JOSEPH v. canmm

